The present invention generally relates to a ratcheting C-clamp. More particularly, the present invention relates to a one-handed bidirectional ratcheting C-clamp capable of tightening a work piece via the ratchet mechanism and a lever and corresponding screw mechanism.
C-clamps are generally known in the art. A conventional C-clamp typically includes a “C” shaped member constructed from cast iron or another hard metal alloy material. One end of the C-shaped member has a threadable hole therein configured to receive a corresponding threaded rod. The rod is screwed through the hole toward an opposite end of a C-shaped member having a corresponding flat surface. The forward motion of the threaded rod is governed by the thread-by-thread screwing mechanism and is typically slow. The distance the rod moves with each turn is limited to the pitch of the screw threads. Faster movement is accomplished by incorporating a nut or other structure that enables only partial threading of the rod. Other mechanisms may allow the rod to completely disengage the threaded C-shaped member for axial movement therein. Accordingly, the flat end of the rod mates with the flat surface of the opposite end of the C-shaped member. Adjustment of the rod in this C-clamp is only accomplished by screwing the rod.
C-clamps are used in industry to secure a work piece or to secure several work pieces together. The work piece is placed between the flat end of the rod and the flat surface of the opposite end of the C-shaped member. The work piece is secured therebetween as the rod is screwed towards the flat surface of the C-shaped member. This squeezing or clamping action prevents movement of the work piece or prevents movement of several work pieces relative to one another. The C-clamp may include a pressure pad or vice jaw to further retain the work piece or the plurality of work pieces.
A common issue with known C-clamps is that the operation requires two hands. One hand holds the C-clamp assembly while the other hand turns a lever mounted to one end of the rod. The lever provides a higher mechanical advantage for screwing the rod through the hole end of the C-clamp. The lever allows the operator to obtain the necessary torque required to securely squeeze the work piece between the flat ends of the C-shaped member and the rod. Thus, a third hand or other retaining device is needed to assist the operator in order to hold the work piece in a steady position so that the operator may close the C-clamp therearound. Improvisations such as using a knee, a jury rig lever temporary welded to a work table, etc. are inadequate substitutes for the third hand. Such improvisations are also hazardous, time consuming and poor substitutes for other methods of holding the work piece in place. An alternative to using a third hand (necessarily requiring incorporation of a second person) is the use of an additional holding or retaining structure employed to clamp or retain the work piece prior to C-clamp application.
A one-hand operated C-clamp known in the art provides a mounted rack-held movable jaw that drops down against a work piece. The movable jaw is operated by gravity. The C-clamp further includes a cam-operated pawl that engages the rack via a hand-squeeze handle. The handle is used to increase the clamping pressure of the jaw against the bottom portion of the C-clamp. The C-clamp is locked into position with one stroke of the hand-squeeze handle. A lever in the jaw head rotates the jaw to obtain proper holding pressure when the clamping movement is insufficient. The C-clamp requires operating the lever with one hand while simultaneously holding the work piece with a second hand. Such a C-clamp is typically mounted to a table or other fixture. A disadvantage of such a C-clamp is that operators are unable to move the C-clamp into confined or narrow spaces where clamping may be desired.